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Why are the cockpit controls of airplanes so complicated?
For a layman like myself, the cockpit of every single modern airplane that I've laid my eyes on seems like a complex, intimidating mess with knobs, buttons, screens and levers literally covering every single square centimeter. Every time when seeing this, from my point of view, chaos of control surfaces and indicators, I'm always thinking to myself "This HAS to be possible to make easier!"
Maybe my intuition is correct. Maybe it isn't. Anyhow, I can see a lot of possible reasons why one actually would want cockpits to be designed in this way. Maybe it makes it harder for an amateur to just wing it (no pun intended) and make it looks like (s)he knows what (s)he's doing. Maybe it forces the pilot to really understand every single nuance of the plane and its operation before even being able to taxiing. Maybe it fosters speed and security in an emergency situation by having everything accessible right away, accessible through muscle memory on the part of the pilot.
Or maybe most cockpit designers like to make the operation of aircraft a pain in the behind for everybody else. I don't know.
What's the design philosophy behind the design of the cockpit controls?

I don't think your "snobbish designers" theory holds water. They're doing everything they can to simplify the cockpit, and they're making good progress. Remember when airliners used to require flight engineers, sometimes more than one? Now it's next to unheard-of. And the newest generation of small jets are usually single-pilot certified!

@dvnrrs Me neither. It was, what you humans normally refers to as, a joke :)

I would say muscle memory has a big part.  I've gone entire flights without reading the labels of the buttons I'm pushing.

@SteveV. yeah,  feeling that much safer now,  thanks :-)

"An aircraft's panel should be as simple as possible, but not simpler."

Because the alternative is an Apple iPlane, which would have one button, a voice input called Siri, and you wouldn't be allowed to decide your flight plan. It would work wonders and millions of people would take to the skies. Simpler is dangerous to wish for at some point!

Because flying is an extremely unnatural thing for a bunch of people and a huge hunk of metal to do.

hmm, the iPlane. Where you have to dig through dozens of layers of "apps" and screens of icons to deploy the flaps, then move up to the top and go back down another tree to lower the gear. Etc. etc.

@Kheldar And you can only fly to airports that have been approved by Apple. And if Apple decides it wants to open its own airport somewhere and charge higher landing fees, you'll have to use that airport.

@reirab At least, contrary to RyanAir, a real company with real planes, Apple doesn't get subventions designed to help small regions take off economically and abuse them to steal business off of bigger hubs, while unfairly competing with other air companies. Business is an interesting world to observe, like a zoo.

@Kheldar -- then again, Ryanair moving in and moving some business to an outlying airport might just be welcome in a busy metro area due to the primary hub being full to the brim with traffic already, while being surrounded by development!

@UnrecognizedFallingObject indeed, though of course other companies would have the same incentive, including the big ones.

@Kheldar -- the need to maintain connections with alliance/codeshare partners and their own long-haul flying, as well as the costs of having the infrastructure already there, tend to keep the "legacy carriers" in the major hubs.

@UnrecognizedFallingObject very good point indeed

Note also that you need all the information to be accessible at a glance in emergency situations where time is precious.   This includes knob settings.  A plane is a complex machine.  Presenting all the information at once is almost by default overwhelming.

Can you maybe add a picture of such a cockpit that stresses your point?

Because airplanes are complicated.

Complexity is nothing more than the agglomeration of simplicity. Seen as a whole by the untrained eye, a car engine seems very complicated, especially when it is running. Apply the ages-old concept of divide and conquer and break it down into its simple components, and the mystery is no more.

I would argue that the controls of an aircraft are not complicated, but rather that they are simply foreign to you.
In the vast majority of cases, the various controls in the aircraft do one thing:  Turn something on, or turn it off.  They are quite simple actually, but what makes it appear complicated to you is that there are so many of them.  As you learn about the airplane (especially modern ones) you will see that these individual controls are grouped together by system, in a way that actually makes pretty good sense.

To put it in perspective, let's say that you had never seen a laptop computer before:

This...  thing (remember, you've never seen one before!) has 94 buttons on the top alone!  It has all kinds of little jacks and plugs on the outside.  It has things that pop open from the side.  It's just...  complicated.
Then someone points out that most of the buttons on the top are buttons that you can press to make a letter show up on the screen.  This takes much of the mystery out of the complicated mess on the top, but then as you start to learn more you figure out that some of the less commonly keys are grouped together by function.  You have the arrow keys, the function keys, the key modifiers, the CD controls...  Suddenly it doesn't seem quite so complicated anymore.
You complain to your friend that the monitor (hey, we've learned a fancy new word!) is a little too small, and they suggest that you hook up an external monitor.  We can do that??  Of course, that's what this port is for.  Cool, now that's one less mystery.  This goes on, and before long you can even pick up a different brand of laptop, with different buttons and pretty much figure it out on your own.  Before long...  the mystery is gone and it's just a laptop computer.

And so it goes with airplanes.  Newer airplanes are being designed with fewer switches and gauges.  Take a look at the progression in the Falcon 900 series aircraft:

Falcon 900B

Falcon 900EX

Falcon 900EX-EASy
Each iteration has fewer and fewer controls and instruments.  You may even say that they look less complicated.  However, I can assure you that each newer model has far more capabilities and a lot more to learn in order to understand and safely fly the airplane.  They each have the full capability of the model before it, along with additional features and more to learn.  Certain systems no longer have switches or dials and you have to look through different menus in order to access them.
Appearances... can be deceiving.

Something worth noting is that as each design iteration gets "simpler" the information desnity on the displays increases. Counter-intuitively it tends to take more training to successfully take advantage of increased information density, but once you have the necessary training there are substantial gains in efficiency (and theoretically safety).

Worth mentioning is that the 900EX-EASy seems to be a somewhat experimental design. I'm not sure if I like it or not; on the one hand, there's less instrument clutter, but on the other hand, while it's true you mostly don't need e.g. engine pressure gauges, when you do need them, you tend to need them in a hurry. I'm not even an amateur pilot, though, so it may be I don't have a useful perspective on the matter. Also, where are the fire handles?

(Also, it occurs to me that you've underplayed your hand by omitting mention of the now-bygone flight engineer position, and the sort of complexity it entailed -- amply exemplified, I think, by this shot of the Concorde cockpit's flight engineer console. Someone who finds today's cockpits overly complex might do well to look back a few decades and see how things have improved since his parents' day.)

As per my comment earlier, the laptop metaphor is all the better that for most users, the one button ipad is a much easier to use computer as the 94-button laptop.

@Kheldar Kind of.  The one button iPad does still have many of the same functions (not all of them), but it is more complicated to find and use them since you have to know which app to start, or which settings to change in order to do  something that a hardware button on the laptop does.  So while it appears easier to use, if you are trying to accomplish a specific task (like say change the volume) it is much harder to accomplish without specialized knowledge.  Even the keyboard is still there (on screen)...  Once you figure out how to access it!

@AaronMiller The engine gauges are on the inside of the Primary Flight Display (the big one in front of each pilot), so not only are they there, but both pilots have their own, right in front of them.

@AaronMiller The fire handles are the one thing that they moved to the overhead panel (and changed them to buttons).  I wouldn't call the EASy cockpit an experimental design.  They have been using it for quite awhile in multiple aircraft types, and recently updated it to EASy II!

Since Aaron's link to the concorde cockpit no longer works I thought I'd put in http://en.wikipedia.org/wiki/File:ConcordeCockpitSinsheim.jpg and I assume the engineers console is the thing on the right of shot...

@Chris It's the underscores. I believe this is the one: http://www.geograph.org.uk/photo/1357498

How do you get up to pee from those seats?

@asawyer Very carefully.  :-)  New pilots on the airplane actually tend to bump their head on the overhead panel and turn things off as they are getting in and out of the cockpit.

I think the mere appearance of the intimidatingly complex cockpit instruments is part of what makes the pilot profession awe striking, even if a pilot doesn't know how to fly but knows how to recognize and use those instruments. If you take a picture of yourself with the instrument panel behind you, and show it to your friends, you feel some pride. :)

As has been pointed out in a previous answer, the cockpit is a user interface. My belief is that it is virtually impossible to design any user interface that is user-friendly to both novice and experienced users, and I question whether you would really even want to do that. For example, in a light single engine aircraft with one fuel tank, a single on/off switch for fuel is understandable for the novice and adequate for the experienced. That same airplane might not have a hydraulic system so there is no need for hydraulic controls.
Now consider an airplane with nine fuel tanks, four hydraulic systems, and eight hydraulic pumps. Possibly you could engineer it such that when everything is working, a single on/off switch for fuel and another for hydraulics would work. However, if you're over an ocean with 400+ souls on board, you need more than everything is working fine or everything is not working fine. You need the ability to keep part of the systems working even when part of them have failed, and for that you need information on each component and the ability to control and/or isolate each component, not to mention understanding the components and how they work together, and how the failure of one can impact the failure of another.
It would be unreasonable to expect a novice to deal with failures of individual system components, and it would be irresponsible to put a novice in charge of such a situation. Thus, right off the bat, we can and should dispense with trying to make the system user-friendly to the novice.
So, we might have a system that seems incomprehensible to the novice, but it is and feels to be the right complexity to the person working with it on a daily basis.
The first airplane I regularly flew as a licensed pilot was a Cessna 150. It quickly became the right size. I decided one day I wanted to check out in a Cessna 172, and that airplane was a "big airplane" for the first flight or two. When I checked out in a 182, I had the complication of a propeller control and a manifold pressure gauge. Hmm, did I really need that? Through the years the airplanes got bigger, but I found that I came to regard the airplane that I was flying as just the right size and no more complicated than it needed be for the task at hand.
When they used a 747 to transport a single passenger, the movie star Rock Hudson, back to the U.S. when he collapsed in Paris, I didn't think that strange. It was just an airplane, and the 747 was that airplane that was the right size for me.

I disagree with your initial assertion that it is virtually impossible to design a user interface that is user friendly to novices and experienced users. The keyboard / mouse combination is a great counter example. A novice can do everything they need to simply by clicking the mouse and pressing buttons according to how they are labelled, and what their screen is telling them to do. An experienced user can use modifier key short cuts, F-keys, macros, scripts, and other advanced options that are not at all obvious or self explanatory to the novice. All from the exact same two input devices.

But to a novice, @JBentley, the keyboard is intimidating and overwhelming. Remember trying to learn to type? I've seen 50+ year old men who have sat in front of a keyboard for half their lives (no longer novices) who still struggle to hunt & peck.

@FreeMan That just reinforces my point further. The 50+ year old men can still use it, in a user friendly way, even though all they've bothered to learn is to hunt and peck. It might be slow, but that's not the same as being difficult. A complete novice, with no skill whatsoever, will not fail to figure out how to make it produce text on the screen, even with no tutor or instruction manual. But for those who put more effort into learning the intricacies (e.g. touch typing, in this example) it becomes more effective, and that is available without any affect on the novice.

@JBentley, keyboard and mouse is not a user interface, just components for building one. You have to look at how the application assigns meaning to the keys and clicks. And there you have applications friendly to ordinary user whose job is something else and professional applications that are never friendly to beginner. Have you seen PhotoShop? Or Blender? They are huge mess of buttons and functions, but all professionals use them, because they are powerful. And applications have the advantage that a beginner can simply ignore the advanced functionality. In aircraft, you can't.

@JanHudec That may be the case (that a beginner can't ignore advanced functionality), but that's widening the scope of the point I was making, which was solely in response to "it is virtually impossible to design any user interface that is user-friendly to both novice and experienced users". I contend that it is actually quite easy to do so. Whether or not you would want to is a separate point, that the answerer did actually make, and I don't dispute.

@JBentley, No, I am not widening anything. I am saying that 1) your example does not qualify as user interface and 2) if we extend it to what is a user interface, it turns out it is hard to make to design user interface that is user-friendly to both novice and experienced users.

@JanHudec I didn't refer to the keyboard  /mouse alone as a UI though. If you re-read my first comment you'll see that it was in the context of things such as "what their screen is telling them to do" and "modifier key short cuts", which relates to your statement that "you have to look at how the application assigns meaning to the keys and clicks. You've provided two counter-examples, but that doesn't disprove my assertion. The UI of a modern OS is an example which is both beginner and advanced user friendly. I am sure you can think of plenty more.

@JBentley, which "modern OS" do you have in mind? Windows is not particularly friendly to beginners and pretty big mess at the expert level, OS X used to be beginner friendly, but mostly at cost of hiding or not having the advanced functionality and GNOME and KDE are always just playing catch up and the guts below them are also big mess. No, sorry, I don't accept your example.

By modern OS I was thinking of Windows, a Linux distro, or OS X. GNOME and KDE are DEs not OSs, but the same principle applies. In KDE for example, a beginner can easily move and resize window around with a mouse. A more advanced user can configure keyboard shortcuts that can place windows onto different screens or portions of a screen. Windows is beginner friendly: my grandmother can use her mouse and keyboard to check her emails. I can do the same task more efficiently because I know my way around the UI better. On a linux distro the balance is more weighted towards the advanced user.

@JBentley As someone who uses a custom-designed "desktop" interface (Fvwm 2 with a heavily customized configuration), I find the "standard" Mac/Windows/Gnome/etc. interfaces to be considerably less user-friendly to me: something as simple as maximizing vertically (two keystrokes for me) either involves non-obvious mouse movements that get in the way of other functionality or doesn't exist at all. I think you've simply seen only one type of "desktop" interface all your life and assumed it was efficient for everyone.

@CurtJ.Sampson On the contrary, you have made an assumption which is not correct. I have used a variety of systems from DOS through to Windows (3.1 through 10), and various flavours of Linux with DEs such as XFCE, KDE, among others. I currently use i3wm, so I appreciate the benefits of  a custom DE configuration aimed at advanced users. But this supports rather than detracts from my case. The same system which supports your DE also supports the "standard" interface as you call it, which is user friendly to beginners.

@JBentley Actually, you're the one making the incorrect assumption here. Everything you've described is basically the same general UI with minor changes in the details, as compared to the one I use. (Fvwm 2 in its default configuration would also fall into that "same type" category.) To give you a small taste of the difference, consider that I have no on-screen "buttons" to maximize, minimize or close windows because using those is so inconvenient (you actually have to reach for a mouse) that they're not even worth the screen real-estate.

@CurtJ.Sampson Yes, I know. As I said, I use i3wm, which works on the same principle. Also as I said, you are using an advanced feature of your OS and that same OS supports the "standard" interface for beginners. You can even if you wish, run an advanced WM on top of a more standard DE, so that you can use both interfaces simultaneously.

@JBentley Sure, you can get alternative UIs on my OS. But you've just undermined your argument: those are different UIs, and they are indeed significantly less friendly to me as well as significantly more friendly to beginners.

@CurtJ.Sampson This may be my fault for editing my comment after you read it, but see my last sentence. See for example, here. When run simultaneously, the beginner is free to ignore the advanced features, as the advanced user is equally free to ignore the basic features. Indeed this is how the majority of people use their machines. In my usage for example, I ignore the mouse 90% of the time, even though it remains available to me.

@CurtJ.Sampson Remember the assertion is that it is virtually impossible to design a UI which is friendly to both categories of user. There only needs to exist one counter example, for that assertion to be proven false. Examples of UIs (such as perhaps you have discovered) which are not friendly to both, do not prove it to be true.

@JBentley The WM is the UI we're talking about, and it's simply not possible to run two at once. You can't both remove the minimize/maximize/close buttons for me and keep them there for someone else. I'm sure that there are some cases of UIs where you might be able to design for both, but there are plenty of other cases where you can't. And I'd argue that especially airplane cockpits of complex, multi-engine commercial transport aircraft fall into the latter category.

@CurtJ.Sampson If your point has boiled down to it being impossible, because it would be too annoying for the advanced user to ignore and not use the buttons that are for the beginners, then fine, we can agree that it is impossible. But I think that is being far too nit-picky. I think that in reality, the advanced user can continue at 99% efficiency and just simply ignore those buttons, albeit he loses a tiny % of his pixels to them (and if it were really that important, I'm user we can imagine creating a keyboard shortcut that turns the icons on and off).

@CurtJ.Sampson In the absence of any counter example for commercial aircraft, I am willing to concede that it may be impossible in this case, although I not completely convinced that we should ever be talking in such absolutes. "Difficult" would be a better choice of word, perhaps. In any case, when it comes to commercial airlines, we don't need to cater towards beginners.

99% of the information provided by all of those gauges, and 90% of the possible positions of all of those controls, are not necessary on a typical flight. You CAN take off, fly, and land, with just the instruments used on an ultralight (or less, if you think about the paramotor folks). But if anything goes wrong, or to squeak out a tiny bit more efficiency, you will want at least some of that extra info and extra control, and you don't know which things you'll need until something goes wrong, so everything is provided.
Analogously, many people who soup up street cars to race them will install many additional gauges and controls, which normal drivers don't want or need. Temperature monitors for specific parts of the car, toggles for different valves and sensors, etc.

It is not only "if anything goes wrong". In an airliner you need all the basic instruments plus the instruments necessary for IFR, the autopilot (not optional when you flight at high altitude), the engine management system, fuel gauges plus sensors and pumps,  the ventilation/pressurization controls, radio + backup system for communications, navigation computer/instruments, control of all the electrics of the plane. Without any of those a commercial airline would be in an emergency.

@MartinArgerami but you still can fly without most of them.

It depends on what you mean by "fly". Keeping it in the air for a little while, yes; performing the usual operations it is designed for, no.

You can also make an analogy with computers. Many people just use them to do basic word processing, web browsing, and email and rarely, if ever, go down into the command shell, adjust configuration file settings, or write shell scripts. These options are there, however, in every PC out there, ready to be used by users that know what they are doing.

To the above, I'd rather compare an airliner left with only ultralight controls to a computer left only with a game controller. Fine within one game, not so much if you need to, say, land.

The controls of an airplane don't have to be complicated. Here is a typical modern glider control panel:

These instruments are:

(top left) Variometer (shows relative climb/sink, only really useful for gliders)
(top centre) Airspeed (required)
(top right) Another variometer (in this airplane, one is mechanical and one is electronic)
(bottom left) Altimeter (required)
(centre) Compass (required)
(bottom centre) Temperature
(bottom right) VHF Radio controls

The instruments labeled (required) above are the minimum necessary for any aircraft. The controls not shown in this picture are:

Control stick
Rudder pedals
Airbrakes
Landing wheel lever

Now, gliders don't typically have engines, cabin pressurisation systems, hydraulic controls, fuel pumps, autopilot, navigational systems (ILS, VOR, DME, etc), HF radio, PA system, fire suppression, and so on. In particular, a modern jet engine (just the engine) is tremendously complicated and has many possible control inputs.
Unlike a road vehicle, if something goes wrong in an aircraft during flight the pilot can't just pull over to the side of the road and call for help (of even just get out and look in the engine compartment). The pilot needs full control over all the aircraft systems, directly from the cockpit, in order to be able to control the aircraft safely in case of an emergency.

Only the legs are somewhat distracting - is that Australia Airlines?

The legs are part of the optional emergency ejection system.

I am not seeing any spider, so definitely not Australia Airlines.

Only one compass?

"The man with one compass knows exactly what his heading is. The man with two is never sure."

The important difference between the variometers is that the left one is energy variometer (only used on gliders, indeed) while the right one is normal vertical speed indicator. They show very different information (and note that they are labelled in different units too).

You forgot to list one of the most important instruments:  the bit of string taped to the canopy :-)

I notice no attitude indicator here; isn't that normally considered an essential instrument on an airplane?

@CurtJ.Sampson: It's not required when you can simply look out the window (under VFR).

Thanks. I was curious enough that I asked this as a question on this site and got some good answers.

There’s quite a difference in designing a user interface for a first-time user compared to an expert. Much of airplane design is only for experts, and the designers are willing to have a steep learning curve if it improves efficiency, ease, and safety once someone is experienced.
I’d also note:

Fewer controls doesn’t mean easier. In a car, for example, a touch-screen display can be much more annoying than a nice set of knobs.
Habits can be formed more easily with different kinds of controls and locations. Designers often deliberately make different controls look and feel different. You don’t want to confuse a gear knob and a flaps knob, for example, so they have different shapes. This can seem overly confusing at first, but really helps build muscle memory.
The location of the controls itself can be very significant. The knobs and switches on the ceiling are likely to be less commonly-used and thus don’t need to be in the direct line of sight.

A touch screen isn't "fewer controls".

As others have pointed out, you can have a pretty simple instrument panel if you go with the bare minimum required instruments on the simplest possible aircraft.
I suspect you're more interested in aircraft with panels like like this one though:

When we think about these aircraft you're actually seeing the "simplified" version - or at least the standardized version.
On the pilot's (left) side, there are six standard flight instruments: an airspeed indicator, an artificial horizon, and an altimeter on the top row, and a turn coordinator, directional gyro, and vertical speed indicator on the bottom. These six instruments in this layout are "the standard six-pack", and without going into what each one does it should suffice to say that they're the instruments a pilot is going to refer to most in flight, so the designers put them right in front of the pilot.
On the bottom of the pilot's side panel are switches for things like the interior and exterior lights, and a key-switch for the ignition (this particular aircraft has about 10 switches - they're all labelled, though you can't read the labels in this picture).
On the co-pilot's (right) side are a bunch more gauges which all have to do with the operation of the engine (the equivalent of the fuel gauge, oil pressure, coolant temperature, and tachometer in a sports car), and two rows of circuit breakers (unlike in a car where the fuse box is hidden away in an aircraft you may need to reset a breaker or replace a fuse in flight, so they're out and accessible - and like the switches they're all labeled).
Most of the time you'll only give this side of the panel an occasional glance during flight - since you don't need to look at this information all the time it's put off on the side "out of the way".
Down the center is the "radio stack" - a compass (up at the top) and a bunch of radios for navigation, communication, and ATC identification. Not "necessary", but helpful.
Between the seats you see a valve for controlling the fuel (the big red thing), and a throttle (the black lever between the seats).

While the panel may look intimidating at first the important thing is that it is fairly well standardized: you can jump into another airplane, look around for a few minutes, and know roughly where everything is and how to operate it. Even without much (any?) experience, you can probably find all the same instruments in roughly the same place in this slightly more robust panel - the biggest difference being that there are "control yokes" instead of sticks, and the addition of a few navigation radios and instruments. Even this DC-3 panel has a strong similarity to the first panel above, even though it's a much more complex aircraft. (The original DC-3 panel image is here - click through and check out the full-size version, you can read all the labels).
In that regard the layout of an aircraft panel is similar to a car's dashboard: You can drive in a Ford Mustang your whole life (the first panel), but if you sat down in a BMW 5-series the controls and instruments would be familiar to you (the second panel). If someone dropped you in a snow plow (the DC-3 panel) you may take a few minutes to look around and make sure you know where everything is, but you will be able to pick out the basic controls and gauges and know what they all do (which by no means implies you could handle driving the snow plow and more than I could handle flying a DC-3, simply that a lot of the knowledge transfers).

I've ignored "glass panel" aircraft in this discussion, but if you look at a bunch if them you'll find that they all have a similar layout (a large artificial horizon with "tapes" showing airspeed, altitude, and heading).

A "glass cockpit" indeed hides a lot of secondary instruments (and maybe controls) that aren't needed all the time, but you still have the main instruments doing about the same thing in about the same place -- at all times.

1948 year train crash in Wädenswil (Switzerland) probably explains why "task-oriented interfaces" may actually be dangerous.
This train had the same control both to apply accelerate and decelerate with its electric engine, depending on the position of the separate switch. Indeed, you either accelerate or decelerate, never do both. Why to have two separate controls? A tiny switch looks enough.
Once, on a steep decline, the driver failed to select the right position of this switch and applied full power instead of braking. 21 killed. If it would have had two very different controls for brake and acceleration, such a mistake would have been much less probable.
So, where practical, it may be better to have more controls that never change they function and always do (or display) the same.

This is the best argument against multi-function, glass-panel, touch-screen type interfaces. "But, last I looked I was on the brake screen... I have no idea how I got to the accelerate screen..."

User interface design is complex. Incredibly complex. In a previous job, my company competed on the consumer market against an established company with an aerospace background. That was visible: their consumer products looked as complex as these cockpits. Ours didn't, because the lead designer was exceptional (think Apple-level UI genius). We learned quite a bit from the competition, understanding how that interface was hindering instead of helping.
Did that mean our product was simpler, could do less? No, in fact not. The main reason was that our UI was task-oriented instead of function-oriented.
If you look at the Falcon pictures above, you see a bit of that change. The classic cockpit is function-oriented. For everything that needs a control, there is a dial. And with lots of functions, there are lots of dials.  Quite a few displays are duplicated because the equipment is duplicated.  To take Terry's example, if you have 8 fuel tanks, there would be 8 gauges.
However, you often use those 8 fuel gauges together, rarely in isolation. For instance, the task "check fuel remaining" sums the results; the "check weight distribution" task focuses on the differences instead of the total. A task-oriented UI works better if it focuses on those tasks.
An additional benefit is that in combination with glass cockpits, you can pull up a big User Interface for the task at hand, since the same space can be reused for other tasks at other times. The classical sets of buttons and switches has a static layout and must share the available space.
As a case for this task-oriented UI, consider AF447. The pilots faced information overload, couldn't identify the task they needed to perform (recover from stall), nor the data they needed for that. Yet any pilot when quizzed could tell you how to recover from a stall, and the plane definitely knew it was in a stall.
Luckily there's hope. The use of checklists is well-established. They're closely tied to tasks. Not identical, some checklists bundle multiple tasks because they happen at the same phase of flight but not for the same reason. Still, the basic concept is that you execute a set of checks and actions which together achieve a single goal. That conceptual model, extended to all tasks should define the cockpit, not so much the physical hardware.

"the plane definitely knew it was in a stall" Not after the aircraft entered alternate law (at 02:10:05 UTC, according to Wikipedia) offering no flight envelope protection, and certainly not after 02:11:40 UTC when "all airspeed indications were now considered invalid by the aircraft's computer due to the high angle of attack". The stall warnings restarted when the aircraft pitch was lowered, when lowering the pitch was the right thing to do, and stopped when the pitch was raised again. Reinforcing the incorrect behavior.

@MichaelKjörling: That appears to be an Airbus design fault: if the AoA (or attitude) is so high that the wings cannot possibly generate enough lift regardless of airspeed, the plane knows it's stalling. The stall determination algorithm should only care about the airspeed if the AoA is low enough that the airspeed matters.

I agree, it sounds like a pretty obvious design flaw, at least in retrospect. This could also likely be alleviated by measuring the AoA over some period of time, say 1-2 seconds (this limit could be dependent on altitude, or altitude and vertical rate), and in case of extreme values acting on the way it is headed (sign of dx/dt) rather than the absolute value (x); if the AoA is near the upper bound of safely measurable and decreasing, then the situation is improving and a warning distinct from the "you are entering stall AoA" warning could be sounded and/or displayed.

The intention of my original comment was to point out that while it's easy to say in retrospect that AF447 was in a stall, at the time the aircraft deemed the data that said it was as invalid, which silenced the stall alarm. Hence, the aircraft was reinforcing the wrong behavior in the pilots -- by pushing the nose down, which would almost certainly have recovered from the stall at the expense of altitude had they only pulled through the maneuver, the AoA warning started sounding, leading to pulling the nose back up: exactly the opposite action compared to what was needed.

Following in the line of reasoning presented by MSalters I would like to add a couple of points.

First of all there is no market pressure for the interfaces to become simple. With cars, boats and other vehicles 'normal' users with minimal training should be able to control them, thus car and boat manufacturers are motivated to make their product as simple as possible to understand. Some do this better than others, but comparing the middle dashboard of old cars with new cars there has been quite a change. In contrast with airplanes, put bluntly, it has already been accepted that a pilot needs a lot of training, so the strong pressure to simplify control and offload work to a computer (from function to task oriented) is simply not there.
Secondly aviation has to live with huge safety expectations. One of the results of this is - according to just a single expert I discussed this with... - that in the development of airplanes changing hardware/software on the control side is not done except if absolutely necessary. Why change something that's working? (even if it's as hole ridden as dutch cheese) And how can you change it if there is a huge checklist of things a human pilot is expected (legally) to do (regardless of a computer being better suited to the task).
And lastly, as pilots have received such exhaustive training it is even harder to innovate in the field, as people who have spend a lot of time on learning something are all the less likely to give it up. Thus making a plane which could be learned to pilot in half the time would be senseless as seniors would refuse to pilot it and juniors would still know how to pilot the old planes.

Oh well, just a few thoughts from the UX/market perspective.

This sounds pretty similar to the (non-existent) evolution of some software, for example Microsoft Word and Microsoft Windows. Just look at the uproar that ensued after Microsoft decided to remove the start button in Windows 8.

Although an airplane cockpit is more complicated than a car or boat interface, the comparison here could be improved because a car can have lots of controls that would be unfamiliar to a novice too: tachometer, oil temperature gauge, battery voltage indicator, tire-pressure monitoring indicator, GPS navigation, odometer, parking brake, shift knob, climate control, etc.

Also, having a computer do stuff is dangerous because it can only do what it is programmed to do.   In an emergency you by defintion is in a unforeseen situation and the pilot need full control without having to fight a computer.

Pilots can't handle anything that is truly unknown and unforeseeable- at most they go to basics which is foreseeable. Pilots are programmed.

This is utterly wrong. Comparing cockpits over the last fifty years, the increasing offloading of work to computers and simplification of interfaces is visible in both the controls themselves and in the reduced size of flight crews. It took a large amount of simplification and automation of the flight interfaces to allow getting rid of the flight engineer, and that was a direct response to market pressure (i.e., demand to reduce the cost of a flight crew).

@CurtJ.Sampson You're absolutely right, it depends a lot on the timeframe you're looking at. At the same time the 737 max shows the market pressure to keep the interface the same. I am not working in this field myself, so I wrote this answer primarily based on a security expert I had spoken with who specifically researched the security (in the sense of hackability) of airplanes and he found a whole bunch of issues with the 3 models he had researched at that point (one which could've most likely caused an airplane to crash). (cont.)

The singular reason he gave for this was that there was strong pressure to not change "safe" but insecure systems. Sikorsky are now able to build helicopters that fully pilot themselves, but there isn't much market interest. I mean, I sincerely don't know how much small airplane controls changed, but the 737 max definitely showed that there is little market pressure to make the job of a pilot a lot easier. Until we are literally able to get rid of pilots making their jobs easier simply doesn't hold a lot of value. Getting rid of flight engineers is a good counter point from longer ago though.

Point is: I would bet everything that it's possible to design an aircraft that's simple enough that you could train a novice to safely fly it fully within a couple of weeks. It would take quite a bit of software engineering, UX changes and policy changes, but there no technical problem which is particularly hard to overcome. Compared to self driving cars (an industry a friend works in) one could even say it's child's play. My point was just that there is no reason to make such a plane. This is btw a very well known problems in many fields with long educations (e.g. medicine).

While there certainly is significant pressure to avoid new stuff because it's not as well tested and debugged (not just in operation, but also usability), that's a component of the overall decisions that in no way completely stops change; it just slows it. My FE example was just one of many: there are literally dozens of other major changes incorporating improvements driven by market pressure over the last 3-4 decades. Consider FADECs, glass cockpits, GPS navigation, electronic flight planning, fly-by-wire; the list goes on and on.

And no, it's not possible to train anybody to fly, except in extremely limited circumstances, in a couple of weeks. I'm afraid you've bought into the "the aircraft can fly itself" fallacy, but even when it looks like it's "flying itself," it's because a pilot programmed it to do specific things that required a lot of pilot knowledge. Setting up an autopilot can take more work and knowledge than hand-flying an aircraft. Check out the description of an autopilot descent at https://www.askthepilot.com/pilotless-planes/ for an example.

@CurtJ.Sampson I wasn't talking about current planes... I was talking about what is and isn't technically doable. There is no market pressure to make pilotless planes (outside of actual drones), as removing a single salary is nothing versus 1) fuel and 2) loss of passengers out of irrational fear. All I am saying that making autonomous cars is many many many orders of magnitude harder and Waymo has that basically working in most but not all settings (and a lot of other teams are seriously working on it as well).

I don't believe that making autonomous cars is harder at all; in fact it seems significantly easier since failure modes are so much easier to deal with. ("You can always just pull over when something breaks.") But I don't think that this comment section is the place to have that discussion. I still stand by my original point: there have been significant and extensive market-driven improvements in aviation interfaces throughout the last half century.

For decades, the design theory of aircraft has been reliability above everything else. As other answers have said, you can't just pull over to the side of the road if you have a problem in flight. Taking off is optional; landing is mandatory.
With that basic mindset, aircraft cockpits are designed with some central principles:

Complete control. By FAA regs, every electrically-powered system on board an aircraft must be able to at least be turned on and off from the cockpit, even if the only way to do that is using the breaker panel. There are times when one instrument interferes with another, or when an instrument malfunctions and sends confusing signals to ground staff. In such cases the offending instrument has to be disabled. Additionally, instruments have to be adjusted and even recalibrated in-flight, so the ability to do so must be a part of their user interface. Lastly, short-circuit failures in-flight can drain the battery or overload the alternator, and so the affected system has to be disabled through the breaker panel to stop the short-circuit.
Rock-solid reliability. Again, you can't just pull over and call a tow-truck when your uber-fancy fly-by-wire system decides to take a break mid-flight. Every switch, button and display in the cockpit has to be rated for thousands of hours of use.
Proven technology over new sweetness. The previous point tends to favor designs with an established pedigree, from entire airframes like the venerable Cessna 172 all the way down to design and production of the toggle switches for the external lights. In the aviation world, you don't just show up with a fancy new touchscreen and make everything that has come before it useless. We're still using instrument technology that was standard on planes by the end of the First World War almost a century ago.
Modular simplicity. Within the confines of a single flight instrument, everything about that instrument should be intuitive to someone with a basic knowledge of how that device is supposed to function, and that knowledge should be as general as possible. That allows the total number of additional flight instruments and other controls to grow as the airplane becomes more complex and the conditions it flies in more demanding, without sacrificing this basic simplicity.

These general concepts lend themselves to a cockpit design where there is a unique display for every piece of information you need to know, and a unique switch, button, knob or lever for every task you might need to perform.
On a glider, that's not much; other than manipulating flight surfaces, your airspeed, altitude, sink rate and a few other measurements are important, and to talk to anyone outside the aircraft you need a radio, but as there's no engine, there's no throttle, no mixture knob, no tachometer and no oil pressure gauge.
All of those controls and gauges become necessary once you have an engine, along with a magnetos switch to control the ignition system, but these additional controls are all you need in something like an ultralight, where you're just flying in the day in good weather.
Flying at night, now you need to control your running and landing lights as well as cabin and panel lights in the cockpit.
Flying in bad weather, you need a few more tools, like an artificial horizon and navigation systems either based on radio ground stations or satellites.
Adding additional features of the powerplant requires the means to control them; variable-pitch propellers (constant-speed) requires a blade pitch control in the cockpit, usually next to the throttle. Adding a second engine means you need a second throttle, mixture knob and tach/oil gauges. Upgrading to jet engines means you need a battery of additional monitoring devices, and before the advent of computer automation, this required a third person to sit on the flight deck just to monitor and maintain the jet engines of a large airliner.
As you can see, complexity of the cockpit increases as you increase the complexity of the machine. A modern airliner is a very complex machine indeed, with hundreds or thousands of miles of electrical wiring in a modern fly-by-wire airframe like the A380 or 787. A 172, not so much, by comparison. A light sport aircraft can be downright carlike; tachometer, spedometer, engine temp, fuel gauge... other than the altimeter, practically everything you'd have access to in a sport aircraft has a direct counterpart in your car.

Well, having that third person on the flight deck is more a function of having more than two engines to juggle -- jet FEs just had to set powers and read checklists, at least if all went well.  Their reciprocating counterparts had to deal with many more controls!  Mixture knobs, cowl flaps, boost controls, you name it!

There is not a single, uniform, design philosophy, for airplane cockpits. The cockpit is a "user interface". Some are easy to use. Others are powerful but confusing for beginners. Some implement standards so that knowledge of one can be applied with any. Some are hodgepodges with no consistency within themselves. Some start with an expresable goal but fail to acheave it. Some are utilitarian objects with controls and indicators in a regular pattern or patterns without regard for how they are comprehended or operated. In many cases, one intent at the beginning of design is merged with other ideals, requirements, informal norms and the like. Cheap and simple to build, and easy to maintain for decades, are as real as imperatives as any other.
In a modern Boeing transport, pilot and copilot each have a semicircular 'wheel' that turns left and right, to deflect the ailerons and regulate rate of roll. The wheel is pulled back or pushed forward to deflect the elevators, which control the angle of attack of the airplane's wing, and thus, taking engine thrust into account, the vehicles's speed, if allowed to stabilize.
The wheels and columns carrying them are interconnected, so moving one control moves the other. Unless some mechanical mishap has locked one in place, in which case an intentionally breakable link can be broken, by force, allowing them to move independently.
Note that the same physical object produces two different kinds of effect, one a rate, with zero near the middle, one, a position, which physics causes to control a rate, with zero beyond one extreme, (speed) not intuitively linked to it. Speed is
also, very strongly, influenced by the engines' throttle position.
In a modern Airbus transport, a one-hand handle off on the outside of each seat pivots at it's base, seeming to "point" the airplane this way or that, but physics still separates the effect of roll, a rate, from the effect of pitch, a position, which, at equilibrium control speed, a rete, but not the intuitively obvious one. However, the captain's handle doesn't move the copilot's handle, so there's no visual or tactile link between the position of one control and the other. If each is moved in the opposite sense of the other, the result is zero roll rate and zero pitch angle.
In a General Dynamics (now Lockheed) F-16, there is a one-hand handle to the right of the pilot's seat, which does not move (in any significant way) but senses the direction the pilot is pushing it and moves the same control surfaces to accomplish the same pitch and roll control.
When 'blind' flying instruments for night and bad weather were invented, the authorities in Great Britain specified that all airplanes bought by the British government would have their blind flying instruments in a standard 2 rows by 3 columns layout. When deHavilland designed the Mosquito, the world's fastest production fighter-bomber at that time, they designed the instrument panel by mounting some other airplane's panel in the middle and adding additional switches, dials, etc, on additional panels left, right and below the "basic 6". The 'borrowed' panel is curved at the top to match the top of some fuselage, but not a Mosquito. Every Mosquito built has a panel with that same, mis-matched, curve. Kinda funny, once you know to look for it.
Cultural norms play a large role too. The USAF studied moving tape/fixed pointer indicators in the 1960s, concluded that pilots could operate more accurately with them than "steam gauge" round instruments. But they cost more because of smaller volumes, more moving parts, they don't fit in a simple, round hole in the panel, and they're "different". Modern glass cockpits mix simulated moving tapes with fixed needles and simulated dials with moving needles. The instruments for some of SpaceShip One's cockpit were horizontal graphics on a laptop computer, which may have been time histories with vertical amplitudes...

A side note regarding round instruments -- the P-51 Mustang had a large bank of secondary gauges off to the side, with "normal" readings at 3 o'clock needle position. The pilot only had to take a brief glance to the side to note if anything wasn't at 3 o'clock and needed further attention. If you were mixing it up with a Me-262, you wouldn't want to have to spend a lot of time reading each gauge.

Good point. Racing cars used to have their tachometers mounted so that max RPM was straight up. In my opinion, round face indicators all pointing the same way are easier to scan than numbers or moving numbers against fixed pointers. USAF were looking at precision, not scan rate and anomaly detection...

The Tiger Moth doesn't have the "standard six" layout. It doesn't have a turn co-ordinator (only a compass) and only the later models have a VSI, earlier ones having the oil temperature gauge where you'd expect the VSI to be. The bank & slip indicator is where you would expect to see the artificial horizon, because there is no artificial horizon. And while the Mosquito's main instrument panel does have a curved top, it has a different instrument layout to the Tiger Moth, and there is no panel above it.

Dan Hulme, you are 100% correct. Thank you!
Here's a Tiger Moth instrument panel:
http://www.aerovintagespares.com/avspares/info_1059.html
Here is a Mosquito instrument panel:
https://goo.gl/images/RZhAik
Whatever the Mosquito basic six panel came from, it's not a Tiger Moth. I've corrected my text.

The design philosophy is:

Keep the operation of each control or indicator as reliable as possible and as simple to use as possible. That there are so many controls and displays in some cockpits is a reflection of the number of things that need to be controlled or monitored.
Put the most important things in the most prominent location for easy reach or reference. For some things, it means duplication for both pilot and co-pilot, increasing the total number of items.
If it's safety-critical, make sure it has a back-up. That can further increase the number of controls and displays.

What to the layperson looks like a jumble actually has logic. When you understand the logic and purpose of the various controls and displays, you will find that there are groupings and standard positionings for certain items. For example: aircraft with side-by-side seating always place engine controls in a console between the pilot and co-pilot. Engine instruments are usually placed above the center console. Front and center for the pilot is the attitude indicator (artificial horizon). Grouped around it are related instruments: altitude indicator, airspeed indicator, heading indicator, rate of climb, and turn and bank; there are no more than a couple of standard layouts for these instruments. The only other controls/instruments that can look busy would be the radio and navigation equipment - often placed above the center console, either above or below the engine instruments. Other controls and indicators will have less standard placement because they may be specific to a type or model of aircraft.
For what it's worth: I acquired a private pilot's license many years ago, have logged very few hours, flew only Cessna 152,172 and a couple of models of single engined Pipers. All of these aircraft have relatively simple control panels. Nevertheless, I can look at a 747 instrument panel and, given a little time, figure out the purpose of everything there. It's because of the standardization of panel layout, and standardization of instrument labeling. An artificial horizon is always recognizable as such, as is an altimeter, airspeed indicator, etc.. Engine instruments are generally (if cryptically) labeled with the parameter they are indicating.

What looks like a jumble to a pilot often has some logic to a design engineer (e.g. in this "shogtun" panel layout the pneumatic (vacuum) instruments are on the top, and the static instruments are along the bottom: Probably makes running the hoses a little easier when you build it, though it's not the ideal layout for a pilot).

@voretaq7  Looks like it was built in the time before ergonomics were given their due, and not exactly done with IMC flight in mind.

In short, aviation, especially at the commercial level, is a little more complex than a car or other vehicle, and even those other vehicle interfaces are complex if you're unfamiliar with them.
A car can have lots of items on it that are intimidating to anyone unfamiliar, and just like an airplane cockpit, there are so many of them that there's no way to "logically" arrange or eliminate most of them.  What are a battery voltage indicator, tachometer, and oil temperature gauge used for?  What are paddle shifters?  What's an odometer and why would it be in a car that already has GPS navigation?  Why do I have a separate foot and parking brake?  What does this Bluetooth phone button do?  Then don't even get me started on some of the exotic controls in race cars, electric vehicles, hybrid vehicles, infotainment devices, etc.  Just as a car can be complicated, I would similarly expect a cockpit to be familiar to someone experienced with it, but complex to someone who hasn't seen it.

That being said, aviation cockpits are more complicated for several reasons that aren't fully covered in other answers:
Navigation, communication, etc. are more complex than other vehicles
Aviation requires some of the same tasks as a car that work in more complicated ways. Simplifying these controls would often require changing the entire aviation industry to reconcile and simplify technologies that were adopted at different times, for different purposes, with different strengths and failure modes.  For example, instead of GPS and dead reckoning being the only navigation options like in your car, in a plane you can have GPS, VOR, DME, ADF, ILS, and sometimes even other navigation options, each with their own indicators and controls. Instead of just using your hands-free bluetooth connection to communicate, you now have the ability to set transponder codes, set up a standby frequency, and check the morse code identifier of the station you're calling, as well as possible datalink options like ACARS.  See the image below for an example of how complicated sucha radio stack can be.  Instead of climate controls for you and maybe even separate ones for the passenger, you also now have separate controls for the cabin and cargo area. Instead of a blind spot warning indicator light, you have TCAS and ADS-B to help you avoid traffic.  Not all aircraft are more complicated like this.  Simpler vehicles like gliders have fewer of these complex controls.

There are lots of functions that are fairly exclusive to aviation
It could be said that due to the very nature of aviation the controls are more complicated.  Due to low visibility flying you need extra indicators like a the artificial horizon. There are indicators for the extra degrees of freedom like slip, angle of attack, and altitude.  Similarly, you have more control surface configurations like flaps, landing gear, and speed brakes in planes than other forms of transportation.  Again, many of these extra complications are not necessary on simpler aircraft like gliders and ultralights.
Then there are the extra features for maintenance controls that make the cockpit more complicated.  As others have pointed out, if almost anything breaks on a car or boat you can get to safety quickly.  In an airplane that isn't true.  As such you need backup backup displays, more complicated fuel flow controls, fire extinguishers, extra gauges to warn about dangerous situations like a turbine temperature gauge, and safety features to disable inoperative systems like circuit breakers and feathering controls.  In summary, for safety you may need manual controls for things that could be automatic, extra displays and indicators, and extra buttons and switches to activate safety features.
So in short, airplane cockpits are complicated for several reasons.  First, they're unfamiliar to you and so of course they seem foreign and confusing.  Second, aviation has developed some complex and often redundant devices for accomplishing even simple tasks like navigation, so simplifying the user interface would either involve removing important features or standardizing, grouping, and unifying industry technologies to eliminate redundancies while maintaining all the strengths of each.  Third, aviation as an industry is more complicated.  Navigating in six degrees of freedom at high altitude in zero visibility requires a little more complexity.  Finally, the high safety demands of aviation demand more controls and indicators to maintain safe flying even in unusual conditions and failure modes.

How many people even know how to use part 21 anymore?

@FreeMan - What the heck are you talking about. Everyone knows that part 21 is the millennial theft deterrent device.  Its like a cheat code for cars. Mine has 6 different settings plus 1 auxiliary.

So. Very. True. @DeanF. Except I made sure that all three of my (near?) millennials know what to do with part 21. 2 of the 3 daily drive one, as do I, though mine only has 5 settings plus Aux.

There is progress please take a look at the ICON A5 and the Cirrus Vision SF50 cockpit controls.
And I agree a lot of Pre-Flight checks and controls could be simplified or computer checked.
The big difference between a car (simple interface) and a plane is if there is an issue with your car you pull it aside and with a plane you drop from the skies :(  although autogyro's like the Cavalon dont have that issue :)

The ICON A5 is also a very lightweight sports aircraft. It's not designed to hold hundreds of passengers at 50,000 feet.


text:
Why are some pitot tubes more prone to icing than others?
I understand that there were several cases pitot tube failure in a certain way.
The pitot tubes were clogged by ice when the airplane was in cold and wet conditions.
The remedy was to exchange the pitot tubes by a different model from a different manufacturer.
As an example, there was an Airworthiness Directive (DGAC 2001-354) applying to the A330 and possibly others, explicitly requiring to replace the model installed when delivered by a specific other model.
The A330 originally came with pitot tubes from Goodrich Sensors and Integrated Systems,  part number 0851GR. The Airworthiness Directive of 2001 required to replace these by pitot tubes made by Thales, part number C16195AA, or a specific, more recent model from Goodrich.
I assume all models from all manufacturers have the same basic construction, like all can be heated, for example.
What is it in the construction of the pitot tubes that makes the difference?
Is it just a design flaw in the Goodrich series that was fixed later? Somehow I expect it to be something more general. Are there other manufacturers building pitot tubes with a similar flaw? (That would be a good reason to require replacement with a specific model.)

I'm not entirely clear what you are asking here.

Your question is almost equivalent to "why some cars are most suseptible to failure than other". There are many design difference and some design choices may be less faulty than other, but there may not be a straight answer for a such wide question.

I see your point - I will make it more clear.  As an example, there was an Airworthiness Directive applying to the A330 and possibly others, explicitly requiring  to replace the model installed when delivered by a specific other model.

@VolkerSiegel if you can provide a link to that AD and edit the question for "Why  is susceptible to icing" this question would be much better.

I'd like to note that the AD you linked to has all Thales C16195AA being replaced by a Goodrich 0851HL and C16195BA parts in positions 1 and 3 being replaced with the same Goodrich pitot tube. I'm trying to find the AD from 2001 you referenced

the thing is that AD 2009-18-08 does identify later changes to the pitot tubes that seems to reverse a previous AD. I'm surprised that they would go back to a model that was previously removed as part of an AD.

no worries, I just wanted to make sure the question was accurate. I'm pretty new to reading ADs, but it seems like these changes were imposed without any verification that the change actually addresses the problem.

Actually the answer is quite complex, but essentially depends on the local aerodynamics, shape of the probe and the anti-icing power (heating).
Imagine an airplane flying around a cloud, it essentially approaches air with small drops of water floating around, those drops of water impact the pitot tube and some of them keep over the pitot tube surface.
Now, the key question is if that water will or will not become ice. That essentially depends how long the water keeps over the surface and the local temperature.
Keeping on the surface depends on the shape of probe and the local pressure. The water temperature will depend on a balance between the external temperature (also dependent on the local pressure) and the balance of power applied to the probe to avoid freezing.
So, the phenomena is quite complex and depends on all of these factors, and the potential case of pitot tubes prone to icing will likely being a condition unexpected and outside margins as all these factors are taken usually into account.

That's indeed more interesting than I hoped for, thanks!

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

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text:
Is there any technical reason that prevents installation of a jet blast deflector at Princess Juliana airport?
A jet blast deflector (JBD) or blast fence is a safety device that redirects the high energy exhaust from a jet engine to prevent property damage and injury.
Regarding the incident on July 13, 2017 at Princess Juliana Airport, I see no jet blast deflector installed. Is there any technical reason that prevents installation of such a safety device?

The airport at Gibraltar[1] has a road crossing the runway, which gets closed whenever a plane is landing. The road and the beach should be closed to avoid such accidents.
[1] https://en.wikipedia.org/wiki/Gibraltar_International_Airport

This person's death is tragic, and probably will cause the whole jet-blast area beach/party scene to be shut down. On the other hand, the free-will dude inside me says that these people are out there because they choose to be, and if they want to assume a negligible-but-potentially-fatal risk, so be it.

They don't have enough warning signs.   They need enough signs to deflect the jet blast!

@BobJarvis Is it really that tragic when someone dies because they did something stupid that there was a warning sign about?

Also based on the video, it seems like it could be more effective to remove that concrete barrier that people can crack their head against when falling, than to close off the whole area.

@immibis Or simply pad it.. which would arrest their motion. We know how to do that so baseball outfielders and gymnasts don't get seriously hurt when they run into a wall. It is a bit irritating that some initial headlines (not the one the OP linked) said that the jet blast itself killed the unfortunate woman, and not cracking her head on something hard.

@immibis: yes, it is. If you want to be smarmy about it and say things like "Well, it was her own fault" you can do that. I'll suggest that a bit of compassion and empathy might make the world a better place. Perhaps you could help?

@immibis Agree with Bob. Would you have the same attitude if someone has died in motorcycle accident? Riding a motorcycle is dangerous as well, yet people do it.

@Utku Depends what they were doing on the motorcycle.

An immobile jet blast deflector could not be built far enough away from the runway end to be safely clear of the landing path. Large airplanes like 747s must touch down pretty close to the near end of the runway, which is right at the edge of the  beach, a blast deflector would be a serious hazard if an airplane came in a bit too low. Here's what I'm talking about:

A static deflector would be extremely close to the path of the landing gear.
It could theoretically be possible to install a retractable one, however sand does not make a good building surface and therefore it would be real engineering challenge.
It seems much more likely that the authorities, if they do anything, will install more fencing or other barriers to deter people from getting so close rather than install a blast deflector. This would be cheaper and achieve the same effect.

While I feel extremely bad for the woman and her family for her death, I hope, unlike what would happen most other places, the authorities point to the LARGE signs warning of the danger, including the possibility of death, and get on with getting on.

Strongly agree with the sentiment of @CGCampbell.  I first saw a video of this practice a few years ago and my reaction was half "Those people are nuts" and half "I wanna try!".

Agreed, @bclarkreston.  If consenting adults want to risk their life doing something that doesn't put other people's physical / mental health in danger, they should in general be allowed to.  This seems to me a lot like people putting on wing-suits and jumping off cliffs to fly though narrow valleys.  People die doing that, but other people keep doing it.  Except maybe this is less obviously dangerous, so people don't understand the risk?  Maybe mountain climbing (not Everest, just smaller safe mountains) would be a better analogy.

Your second sentence isn't true: https://aviation.stackexchange.com/questions/26141/do-large-airliners-have-a-short-field-landing-technique

What about a protection not taller than the fence, and just behind it? Maybe turbulence from deflectors would create a different problem to the airport?

@CGCampbell The authorities have been warned after an incident around 2012 that the signs were inadequate safety measures since "nobody followed the signs' advice anyway". The court agreed. So, it's likely they'll have to implement additional measures this time.

Great...another victory for the nanny state.

I think a much better way to deal with it would be to make is safer to view rather than prevent it. Some people come to the island with that one spot in mind, which is probably why the authorities haven't prevented access.

In some places in the UK where a road is close to the end of a runway we use level-crossing style stop lights which are illuminated when an aircraft lands or takes off, though that wouldn't immediately solve the pedestrian issue without enforcement. See this example at Doncaster Sheffield Robin Hood Airport: https://www.google.co.uk/maps/@53.4624442,-1.015766,3a,75y,107h,84.93t/data=!3m6!1e1!3m4!1sNPUUKta0-jaNsIzOooma3A!2e0!7i13312!8i6656

Pedestrians are another thing entirely @KallumTanton, Clacton airfield has a pedestrian footpath going across the runway, makes things interesting occasionally.

@GdD Ha, that is interesting. I was hoping to see some text painted onto the ground saying "Look Left. And Right. And Up..."

There's big, bright signs on the footpath as you approach the runway, but it doesn't stop people from blundering on when you're on final.

@KallumTanton  From seeing a few youtube videos of less serious mishaps there are some less silly things that could be done for safety.  Removing the raised curb/low wall between the paved area and sand and the one in the middle of the paved area would help.  I saw several people go flying and come to an abrupt stop on one of them.

Just looking at that picture, I wonder how many of those beachgoers get hit by landing gear?

@jamesqf as dramatic as it seems, the answer is zero.

I don't know exactly if or how it applies to this case, but I know there is something called the "assumption of risk doctrine" which means that an entity can't be held liable for injuries from a risk that couldn't have been removed or mitigated without making the activity impossible or pointless (e.g. not fun). Usually it is applied to participation in sports, e.g. you can't sue the organizers of a baseball league if you get hit with a baseball.

Huh?  there's already a fence there - why not just build a deflector as tall as the fence.  (Essentially - "make the fence solid".)

To answer your question directly, the only technical limitation would be the height of the blast deflector due to landing aircraft, but otherwise there is no technical limitation. Landing aircraft have to land beyond the displaced threshold  which is indicated by the arrows. The beginning of the runway is located 500 ft beyond the fence (see google maps photo below), so a 6 to 8 ft tall blast deflector at the fence would pose little risk to landing aircraft, while at the same time deflecting the jet blast from the departing aircraft that are allowed to use the displaced threshold for takeoffs.

They could build a modified jet blast deflector that is no higher than the chain linked fence that separates the airport from the public beach, it would reduce some of the blast that is received at ground level where people are standing. They could make a deflector that is a little shorter than these:

However, this is a pretty big tourist attraction, and there are plenty of warning signs. Its no different than people going on vacations to Yosemite, every year someone slips and falls to their death while walking on a slippery trail to see one of the water falls.

I believe your second sentence is the primary reason: it's not just a tourist attraction, it's a big one for them, and apparently a reason that some tourists specifically go there - the planes get real close to the beach. Sadly, the rationale behind keeping people away from the end of runways is now more evident.

Yup. It is no different than a roller coaster. Roller coasters give riders a thrill, and once in a while someone gets killed. On this island the signs clearly state the danger so each person is exposing themselves to a known risk, just like roller coaster riders. I say, leave it, as is.

But consider the difference between landing gear hitting a chain link fence, and hitting a solid blast deflector.

True, but landing gear hitting the chain link fence is not reported as problem at this airport, and blast deflectors don't have to be built of solid material like concrete, often times you will see deflectors at airports made of thin corrugated sheet metal. Still will cause damage if struck, but can be engineer to give way if hit in direction of landing. Additionally, they could build a retractable one like is used on aircraft carriers and only deploy it for take-offs when jet blast is most intense.

@tj1000 - Precisely this. They could, but they don't want to. The occasional tourist death is the price you pay for thousands of pounds a day of tourist money. The fenceline is a major draw for the area.

I kind of want to go there myself now.

It's a wonderful destination. Nothing beats the Caribbean.

Since I wrote this answer this is at least the second fatality on at an amusement park in the US, http://www.cnn.com/2017/07/27/us/ohio-state-fair-ride-disaster/index.html, so apparently Princess Juliana airport is at least as safe if not safer than amusement parks.

One also needs to remember it was not the jet blast that killed this unfortunate lady (condolences to family), but rather striking the rather awkward and hard retaining wall behind her.
Similar incident...
Although a small deflection fence would not be a bad idea, and could be built to be no higher than the current chain link fence, the least they could do is remove the hard wall that is the real killer.

The question asked if "any technical reason prevents" building a blast deflector. This answer doesn't look at technical reasons. Instead, it is discussion about an accident. A bit off-topic.

@JimDeLaHunt as I said a small one is plausible.. it would need to be no higher than the current fence.

@JimDeLaHunt: Classic X-Y problem. This answer is on topic.

authors: Bob Jarvis - Слава Україні

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text:
Is there a maximum length for NOTAM?
I see some very long NOTAM messages describing a whole section of arrival or departing procedure.
Is there a standard limiting how long a NOTAM can be? In computing I usually see limits in bytes, is there such a limit on NOTAM?

longest I’ve ever seen was 1.5 pages A5 on very small print, so I guess NO :-(

The EAA Airventure NOTAM usually runs around 32 pages every year.

According to an FAA guide to creating NOTAMs (see pages 14 and 21), the "condition text", i.e. the body of the NOTAM...

has a max length around 1200 alpha-numeric characters. If necessary,
  the system will allow a user to create up to ten parts with 1200
  characters each

But, that doesn't include other parts of the NOTAM, like location, date/time, graphical elements etc. I don't know if there's a limit (in kB?) for the complete NOTAM file or not; the document doesn't seem to mention anything about that. It also isn't clear from the FAA document if the ~12,000 characters is a format limitation/specification, or a tool limitation.


text:
What exactly is a BITE?
I read that with each LRU or Module in the IMA it is associated a BITE, Built-in-test Equipment.
Can you describe more in detail what it is and which is its scope?

Built In Test Equipment is part of a system that monitors the correct functioning of that system. It produces an alert if part of the system fails to fulfil its function.
An example would be a system with two sets of memory chips; the BITE would copy all data to set 1, then test memory set 2 by writing and reading various test patterns. If the read pattern is different than pattern written, there is a memory error. If so, an alert is raised. If not, all data is copied to set 2, and set 1 will be tested. This is procedure is repeated at specific intervals.
Another example would be a watchdog timer which triggers a signal if a timer runs out. If the system is working correctly, it will reset the timer before it runs out. The signal from the watchdog can then for example reset the hardware, take some corrective action or raise an alert.


text:
Which FAA or EASA regulation does prevent a high wing to cross the passenger compartment?
I'm looking for reference subpart and eventually chapter in either FAA or EASA regulation where it is stated that for passenger aircraft with high wing passenger compartment can not be interrupted by fuselage-passing wing, so the wing must be placed above the fuselage (with additional fairing thus increasing drag and weight - eg. ATR-42).
I know this is quite obvious but I need a regulation reference for a report.

There is no reference to such a regulation in the design reference books that I have. As I remember, in the F27 the high wing did make the passengers tuck their head in when walking to the rear seats: the wing does cross the fuselage, which makes for a much lighter construction than when placing the wing on top of the fuselage.
Image source
There is also no regulation stating a minimum height between floor and ceiling.
There is statistical data on average passenger length, and design departments of aircraft manufacturers are very much concerned with passenger appeal. So they may be instructing the construction department that the wing must be placed on top of the fuselage, despite the weight penalty, in order to increase market share. Populations are getting taller over time.


text:
Why there are more requirements for being PIC of the airliner above FL200?
From another answer:

Because there are first officers who legally can't be PIC of an
  airliner above FL200...

Why more experience is required to fly the airliner above I assume 6096 meters? I would expect, taking off and flying close to terrain should need more experience.

Link to the answer?

Only thing I can think of is 14 CFR 61.31(g): "no person may act as pilot in command of a pressurized aircraft (an aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL), unless that person has received and logged ground training from an authorized instructor and obtained an endorsement in the person's logbook..."

Note there is often a difference between PIC and the guy flying the thing.

@Ben the other guy (flying the thing) is often called Pilot Operating or Pilot Assisting.

Why more experience is required to fly the airliner above I assume 6096 meters? I would expect, taking off and flying close to terrain should need more experience.

I'm unaware of any regulation that requires a minimum number of hours to be a captain or first officer above FL200. That doesn't mean there aren't such, just that I don't know of them.
It's not that that taking off and flying close to terrain requires more or less experience, but that safely operating at high altitude typically involves a different set of knowledge and experience than operating at low altitude. A seasoned bush pilot who does only that would be ill equipped to suddenly become the captain of a 747 at 35,000 feet, just as the 747 captain who had never been a bush pilot would be ill equipped to scud run through a valley to land on a remote airstrip.
Part of the difference between two such pilots is, of course, a matter of a propeller airplane versus a jet, a slow airplane versus a fast, and the differing complexities of their aircraft. In addition to those differences, though, the environment that they typically operate in and indeed the altitude itself makes things different. The nature of the emergencies they can possibly face are also different.
Offhand I can think of three things the typical low altitude pilot doesn't have to contend with that the high altitude pilot does. There are certainly more.

Oxygen considerations, in other words what you need to do if you suddenly don't have it at a breathable pressure. Probably never going to happen, but the high altitude pilot trains for it.
Regular operation in or close to the coffin corner. If you're unfamiliar with the term,  Wikipedia has a reasonable explanation as well as
this question.
A whole different situational awareness environment than the low altitude pilot. For example, I used to do a flight from Sao Paulo to Miami. Two other carriers had flights scheduled that went out immediately before us, also 747s. Everybody was always heavy, which meant the first guy out got the highest cruise altitude available for the weight we were all at approximately, the second guy 2,000 feet below that, and then us sucking fuel 4,000 feet lower than the first. However, I knew that if I could open up the distance between myself and the second guy, I could get a clearance through the second guy's altitude to the first guy's altitude since there was enough time/distance between us. So what I would do was to climb at best angle rather than best rate. Then, if the weather was good (i.e. no turbulence) and I had the engines for it, it took very little fuel burn before I would able to get 2,000 feet higher if I was willing to accept slightly lesser protection from the top of the coffin corner. Sometimes that would work out, sometimes not, but it always got us at least up to the first guy's altitude. And on rare occasions, it meant we reached Miami before either of the other two.

What does "sometimes that would work out, sometimes not" mean? I assume you didn't crash... :)

@yshavit I was referring to the fact that it was not unusual for things not to work out as expected. Sometimes using best angle rather than best rate wouldn't open up enough space between me and the 2nd guy, or maybe after reaching the 1st guy's flight level, he would be able to climb before I was, or weather made lessening the margin to the top of the coffin corner inadvisable, or controllers that were uncooperative. I perhaps shouldn't have used such a complicated example, but I felt it did illustrate that high altitude flying is markedly different from operating at low altitude.

Oh okay, so it's a matter of doing the calculations and then deciding not to attempt it? I thought you meant you attempted the climb, and then found yourself on the wrong side of the coffin corner in a fully loaded 747. Which sounds like bad news bears to me, though I don't really know. (For all I know, it might just feel like a bit of mild turbulence to a passenger, and then you recover and we don't even know what happened.)

@yshavit You are correct. One would never try to get above the top of the coffin corner. You can't do it. You will stall with possibly catastrophic results. It would be a very hair ride at the very least. 1.3g protection was the normal. In still air expected to remain the same and with no expectations of having to do significant turning, I was willing to accept less than 1.3g, but never less than 1.2g and that only for a short time. If you're unfamiliar with that terminology, Google "1.3g protection at high altitude" and you'll see links to good info.

I'll look that up, thanks!

@Terry: Technically, you can temporarily climb above the coffin corner (by zoom-climbing from a considerably lower altitude), but you can't maintain flight up there.

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text:
Could a big plane glide significant distances, same a ordinary glider (1000 km or about)?
Seems that a usual glider is not limited by its glide descent rate and can fly much more than this. It uses air masses that move upward to gain the altitude.

Are these effects limited by the size of the plane?
Could an airliner gain altitude for free using these "upward blowing winds"?
Could an airliner glide 1,000 km?

Are you asking specifically about "gaining altitude" or extending the glide because there is some upwards air movement? The answer to both is yes.  What do you mean by "significant"?

Note that gliders can not glide for 1000km.  Gliders go upwards using thermals.  (This is no different from going upwards, using an engine.) The whole sport of gliding is about finding and using thermals.

No, there's no way an airliner can glide 1000km, this is because its wing is designed for fast cruising speeds, and it's much heavier compared to the lift generated than a glider. Gliders are light and have huge wings for their weight, which means they can get lifted by powerful air currents. An airliner is not going to be able to do that.
The longest glide of an airliner I know of was Air Transat 236, which glided about 98 miles (almost 160km) from cruising altitude to the Azores after it ran out of fuel. The captain was an experience glider pilot. That is really about the limit.
Keep in mind that there's nothing ordinary about 1000km in a glider! 1000km is a very long distance and you'd need a very good glider and a very experienced pilot in just the right conditions.

The linked Wikipedia article states: "In about 19 minutes, Piché and De Jager flew their plane without power some 120 km (75 miles), further than any passenger jet in history". How does this jibe with the gliding distance mentioned in the answer?

98 miles was from memory, looking at it again I se multiple reports, some up to 100. I think it's hard to say because the pilot did a 360 degree turn to lose altitude and had to fly farther to line up with the runway.

round numbers: 30,000 feet of altitude lost for 100 miles or 528,000 feet (assuming statute miles) of ground covered = 17.6:1 glide ratio. Not as good as a glider, but not bad for something moving through the air at a couple of hundred knots or more.

Say @AnthonyX actually what is the glide ratio for a good glider?  Actually I just googled and it appears to be 40 or even more - sounds about right?

There was also the infamous Gimli Glider, which managed a glide ratio of about 12:1 - slowed for approach with a crossed-controls crab (instead of s-turns), but also a great example of an ex-glider pilot taking in a heavy from altitude with no engines.

Most modern gliders are at least 40, some more @JoeBlow.

For the record, the official accident report on Air Transat 236 says that the engines flamed out 65 nautical miles (75 statute miles, or 120 km) from Lajes.  However, it did fly a greater distance than in order this to lose altitude.  The plane was at FL 345 when the final engine flamed out.

The famous "Glider 747" British Airways Flight 9 flight lost all four engines after flying into volcanic ash, but managed to restart two engines. "The flight crew quickly determined that the aircraft was capable of gliding for 23 minutes and covering 91 nautical miles (169 km) from its flight level of 37,000 feet (11,000 m)"   https://en.wikipedia.org/wiki/British_Airways_Flight_9  Also of interest see https://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding

First, the 1000 km glider trip requires three prerequisites:

Excellent weather for the whole of the trip. Strong thermals caused by lots of sun, a high cloud base and an unstable atmospheric thermal gradient. No precipitation or shielding by cirrus clouds anywhere along the route. Or you limit your trip to a back-and-forth along a mountain ridge.
A good pilot. The fraction of pilots who can reliably fly a distance of 1000 km or more is less than 1% of the total glider pilot population.
A good glider with water ballast.

Next, the sink speed of aircraft limits their capability of sustaining flight in thermals. In Europe 5 m/s is already a very strong thermal, and ideal locations like Australia or Namibia create thermals of 8 to 10 m/s strength. If your aircraft sinks at that speed or faster, flying in a thermal will only delay the time until all altitude is used up. In order to cover some distance, the sink speed must be considerably lower so that altitude lost in a glide can be regained in the next thermal.
The factors which control sink speed are:

Low wing loading: Higher wing loading means higher flight speed and, consequently, higher sink speed.
Low span loading: The less mass must be supported per unit of wingspan, the lower the induced drag will be. At the low speed of the minimum sink rate the induced drag is dominant.
High maximum lift coefficient: The higher the maximum lift coefficient, the slower the flight speed and the smaller the turn radius will be. Thermals are limited in size and it is immensely useful when the turn radius fits inside the thermal.

In order to fly fast enough to cover the 1000 km in a single day it is helpful to have

High wing loading: This is helpful to shift the best L/D ratio to a higher flight speed, so the time spent in a glide can be shorter.
Low zero-lift drag: In order to reach the next thermal with minimum delay, you need to fly faster than at best L/D. Now drag is dominated by the zero-lift drag.
High altitude, so the lower density requires a higher true air speed.

The last condition is the absolute size of the aircraft: Smaller aircraft can fly in narrower circles. Only in ridge and wave updrafts will the size not matter. Bigger aircraft need more time and space for maneuvering, so they will be less able to adapt their flight path to local updrafts.
These conflicting demands will result in a narrow range of characteristics: The aircraft will have a wing loading somewhere around 50 kg/m², a zero-lift drag coefficient of 0.08 or less and an aspect ratio of 20 or more. Its total mass will be less than 1 ton. In short, the airliner-sized aircraft will not be able to profit from updrafts except for reducing sink when flying at the windward side of a mountain range, or the lee waves high up behind the mountains.

Another way to glide long distances would be to use mountain waves, though of course that severly restricts your choice of flight path.  I don't think it would be that difficult to fly the length of the Sierra Nevada, given the right wind conditions.

@jamesqf: The updrafts in mountain waves are normally much less than what can be found close to the ridge, so I did not add this case. Of course, flying in a mountain wave will also reduce sink speed. Karl Striedieck flew more than 1600 km once in one day by running his ASW-17 up and down the Appalachians.

@PeterKämpf: but Klauss Ohlmann flew more than 3000 km in the wave in Argentina. These days, most gliding records have been achieved flying wave. As for the intensity, the current 100km FAI triangle for PW5 is 137km/h, mostly flown with spoilers open.

@MartinArgerami: You are right, flying in waves allows a much higher true air speed. However, high TAS means high sink rate, so the wave must be very strong. I added wave lift for a more complete answer.

Summary: (a) no; (b) not to any significant extent; (c) no, due to (b).  You'd get about 80 miles / 130 km from cruise altitude.
Any aircraft can glide, whether or not it is designed to be powered.  The two main factors that determine glide distance over ground are glide ratio, and sink rate.
Glide ratio is the horizontal distance travel per unit height.  A modern club-level glider has a glide ratio of about 40 to 1: it will glide 40 feet forward for every foot of altitude.  High performance gliders approach 60:1, old basic trainers closer to 20:1.  The glide ratio can also be expressed as the ratio of lift over drag, or L/D.  There is one speed at which L/D is optimised, and this is the speed at which you will cover the greatest distance for a given altitude.  In gliding we call this speed "Best L/D" and in still air it is the most efficient speed to fly when you want to cover ground (such as between lift sources).
You see many unsubstantiated figures for airliner L/D ratios, anywhere from 10 to the high 20s. Given that to test this you would have to stop the engines entirely, needless to say it is very seldom tested! The famous Gimli Glider (a 767) achieved about 12:1 which sounds pretty good for dragging those huge engines through the air.  That glide was flown at 220 knots based on the judgement of the captain, an experienced glider pilot.
The interesting thing about L/D is that it depends solely on the aerodynamics of the aircraft, and the airspeed.  Weight does not affect L/D, so claims that "gliders are light" are misleading.  Increasing weight increases the best L/D speed, and (solely as a consequence of the higher speed) the sink rate, but has no effect on the glide ratio.  In fact in the right conditions, competition gliders are often ballasted with hundreds of pounds of water to increase their best L/D speed, and so get you round a course faster.
So in still air, from say 36,000 feet that 767 could glide about 12 times its altitude: 70 nautical (80 statute) miles.
But what about lift?  Gliders gain altitude by flying in rising air: thermal, ridge, or wave lift.  Lift can vary from 100 ft/min (a weak thermal) up to 1,000 ft/min (strong wave lift).  So a 40:1 glider flying at its best L/D of about 60 knots, is going down through the air at 60/40 = 1.5 knots or about 150 ft/min.  Any time you are flying through air that is rising faster than 150 ft/min, you will climb.  That's how long duration gliding flights are achieved.
The catch with the airliner is that it is gliding at 220 knots at 12:1, so it is sinking at 18 knots, or 1,800 feet per minute.  Except in unusual conditions the aircraft is unlikely to fly through much more than a few hundred fpm of lift on average, at very best.  So lift can be largely discounted and the distance covered over the ground stays around 80 statute miles from cruise altitude.

Are these effects limited by the size of the plane?

Yes and No. Thermals are usually quite small. Even gliders have to fly slow and bank hard. Squall lines and mountain waves will be good for airliner as well.

Could an airliner gain altitude for free using these "upward blowing
  winds"?

Yes! Why not? The only problem is that they have to fly fast compared to gliders to stay in the air. If you fly fast your descent rate is big. The same applies to gliders. So airlines will need very strong uplift currents. I think it should be possible to fly a long very strong cold front or mountain wave or maybe under super cell. But this kind of weather happens very rarely. And it's DANGEROUS

Could an airliner glide 1,000 km?

Theoretically yes. If you find extremely active cold front with squall line 1000 km in length. Though I don't know if this ever happened on planet earth.

As it was discussed here, a Sud-Aviation Caravelle made an experimental demonstration gliding flight of many km, starting at a very high altitude and in special conditions; also, I was told by a pilot of having flown, in a very hot summer day, an Spanish made version of Ju-52 over the Pirineos mountains, with its three engines idling of at full stop, just on an ascending air current, same as gliders; sorry, I can't remember his name (Galve? Calderón?). No more accurate references right now.


text:
Do designers use the same RAM (Radar Absorbing Material) coating across the length and breadth of a fighter aircraft?
I was looking at this image:

Image from Wikipedia
and couldn't help notice that the RAM coating looks different on the vertical/horizontal stabilizers and wings compared to the fuselage.
Given the fact that there are different types of RAM, such as iron ball paint absorber, foam absorber, etc... Are different types of RAMs being used in order to achieve stealth?

You have posed a question that unless covered by published research addressing the topic the answer is likely trade secret and or state secret.  Though intuitively the answer is likely that yes different materials will be used due to the way propagating radar signals hit and reflect the aircraft.

Personally I can't help but notice that the RAM coating looks exactly the same on the wings and stabilizers as it does on the fuselage. Except for colour, but the colour is just an added pigment and the boundaries between the colours don't match any boundaries on the structure anyway.

I'm with @JanHudec, I don't know how you're seeing any different in the RAM coatings. Can you tell  us what you're looking at to identify this?

@FreeMan: I see that there are some patches on the wings and the fuselage. Gives the impression that some type of paint has been spilled on those parts.

According to this article and this book, they use a greater amount of wide-band structural RAM on the wing's edges, whereas they use a ceramic-matrix RAM on the exhaust nozzles. Not only is that the case, but the actual edges have proprietary material designed to be stronger, and have a different radar signature. Although, what you're seeing is probably a combination of the paint job as well as the material, considering the F-22's stealth is not only an aspect of radar, but also visibility.
Most of the stealth of the F-22 comes from the physical shape of the F-22, and reducing its radar cross-section. There are also specialized materials that assist in obscuring its infrared signature. The topcoat, a type of paint, assists in reducing the infrared signature, especially.

To complete your answer: It seems from the article you cite that most of the surface is just paint: A new type of paint, or topcoat, increases the F-22 Raptor's stealthiness by reducing its vulnerability to infrared threats, not RAM (except for what you wrote). In addition the same article explain how most of the radar stealth is achieved using aircraft shape rather than materials.

@Sargun Dhillon: What is ' wide-band structural RAM '?